Connecting to different ports via scp and ssh - why a different flag?

Question

I routinely run sshd on a non-standard port (ie, not 22).

When ssh-ing to my machine I use the -p flag. However, when using scp, the flag is -P (lowercase vs uppercase).

Since they come out of the same suite, why would then not use the same flag capitalization? Is it really just because two different folks wrote it? Neither uses the other form of "p" for anything - wouldn't it make sense for them to work identically*?

---

*_{^{I know - I could modify the source and have a package that accepted both forms: but that does not solve the upstream issue, nor would I expect my patch submission to ever make it into the trunk code (though I'll be giving it a shot).}}

Answer 1

My guess... and this is only a guess... is that -p was already used by rcp for the current meaning of "Preserves modification times, access times, and modes from the original file." And since scp was written to be a drop-in secure replacement for rcp, it was important to honor that flag as rcp understood it. This meant that the option of using a non-standard port had to use another flag.

EDIT: Possible wrapper to convert -P to -p for ssh. It should handle the common cases, but it's not thoroughly tested. To handle even the strangest cases, something that does proper command-line interpretation (such as perl's Getopt modules) would be better.

#!/bin/bash

for x in "$@"; do
    if [ "$END"x == "x" ]; then
        case $x in
            "-P") x="-p" ;;
            "--") END=1 ;;
        esac
    fi
    ARGS="$ARGS $x"
done

ssh $ARGS